The instrument consists of a wooden-framed sound box to which two strings are attached. It is held nearly upright with the sound box in the musician's lap or between the musician's legs. The strings are made from hairs from horses' tails, strung parallel, and run over a wooden bridge on the body up a long neck to the two tuning pegs in the scroll, which is always carved into the form of a horse's head.
The bow is loosely strung with horse hair coated with larch or cedarwood resin, and is held from underneath with the right hand. The underhand grip enables the hand to tighten the loose hair of the bow, allowing very fine control of the instrument's timbre.
The larger of the two strings has 130 hairs from a 's tail, while the "female" string has 105 hairs from a 's tail. Traditionally, the strings were tuned a apart, though in modern music they are more often tuned a apart. The strings are stopped either by pinching them in the joints of the index and middle fingers, or by pinching them between the nail of the little finger and the pad of the ring finger.
Traditionally, the frame would have been covered with camel, goat, or sheep skin, in which case a small opening would be left in back, but in modern times, an all-wood is more common, in a style similar to European stringed instruments, including the carved f-holes.
Morin khuur vary in form depending on region. The Instruments from central Mongolia tend to have larger bodies and thus possess more volume than the smaller-bodied instruments of Inner Mongolia. Morin khuurs built deeper in China also tend to be of poorer quality construction than their northern cousins. In Tuva the morin khuur is sometimes used in place of the igil.
The morin khuur is one of the Masterpieces of the Oral and Intangible Heritage of Humanity identified by .
Among the Chinese, the matouqin is one of several instruments in the huqin family which also includes the erhu.
One legend about the origin of the morin khuur is that a shepherd named Kuku Namjil received the gift of a magical winged horse; he would mount it at night and fly to meet his beloved. A jealous woman had the horse’s wings cut off, so that the horse fell from the air and died. The grieving shepherd made a horsehead fiddle from the now-wingless horse's bones, and used it to play poignant songs about his horse.
Another legend credits the invention of the morin khuur to a boy named Sükhe . After a wicked lord slew the boy's prized white horse, the horse's spirit came to Sükhe in a dream and instructed him to make an instrument from the horse's body, so the two could still be together and neither would be lonely. So the first morin khuur was assembled, with horse bones as its neck, horsehair strings, horse skin covering its wooden soundbox, and its scroll carved into the shape of a horse head.
Chinese history credits the evolution of the matouqin from the xiqin , a family of instruments found around the Xilamulun River valley in northeast China. It was originally associated with the people. In 1105 , it was described as a foreign, two-stringed lute in an encyclopedic work on music called ''Yue Shu'' by Chen Yang. Though it should be explained that the morin khuur is a instrument and not Chinese. Most ethnomusicologists now agree that any Chinese theories on the origin of the morin khuur are not based in historical fact.
The fact that most of the Turkic neighbors of the Mongols possess similar horse hair instruments points to a possible origin amongst the Mongolian peoples that once inhabited the Mongolian Steppe and migrated to the Turkic regions of Tuva, Kazakhstan and Kyrgyzstan. This is considered a far more reasonable theory than any Chinese claim of origin for the morin khuur.